The broad research objectives are concerned with investigations at the molecular-biochemical level of the mechanism of RNA tumor virus replication and cell transformation. The specific aims will be directed toward the elucidation of the following areas: 1) The action of reverse transcriptase will be investigated with specific attention to the influence of ancillary protein (such as the AMV stimulatory protein) on the extent and size of DNA transcript products formed in vitro in the presence of 60S AMV RNA. 2) Investigation of the pathway of tumor viral RNA replication in infected cells. We will define intermediates in RNA replication and elucidate how viral genetic information is integrated into the host cell chromosome.